Recently, there has been an increasing number of surgeons using clips, in lieu of conventional suture ties, to occlude blood vessels and the like. In a typical surgical procedure, many veins, arteries and blood vessels must be tied off, prior to the severing thereof, in order to reach the surgical site. This is an often difficult and time-consuming procedure, since many vessels are located in areas where there is little room to work. It is important that the occlusion be positive to minimize bleeding and, due to the fact that once severed, the blood-carrying vessels tend to retract into surrounding tissue and are difficult to retrieve. As used herein and in the claims, the terms "vessel" and "vessels" should be considered in the broad sense to be inclusive of veins, arteries and the like, to which ligator clips are normally applied.
Prior art workers have devised numerous types of surgical ligating instruments designed to clamp blood vessels. There are, for example, reusable, permanent-type ligating instruments, and instruments which are intended to be disposed of after use. There are also ligating instruments wherein each clip is individually loaded in the instrument. Other ligating instruments utilize pre-sterilized cartridges holding a multiplicity of clips. Yet another general class of ligating instruments is provided with a magazine within the instrument containing a plurality of clips.
The teachings of the present invention are applicable to ligating instruments of the general type having a pair of clamping jaws and a pusher by which a clip is located in position between the jaws, ready to be clamped about a blood vessel or the like. While not intended to be so limited, for purposes of an exemplary showing, the teachings of the present invention will be described in their application to a disposable surgical ligator of the type taught in the above mentioned co-pending application Ser. No. 435,380. The teachings of this co-pending application are incorporated herein by reference.
Briefly, the disposable ligator of the co-pending application comprises a first handle terminating at its forward end in a first jaw. A second jaw is pivotally mounted to the first handle so as to cooperate with the first jaw. A second handle is pivotally mounted at its forward end to the first handle and is provided with a lug to actuate the second jaw. The handles are shiftable between open and closed positions, and shift the first and second jaws between open and closed, clip-clamping positions.
A clip tube or magazine, containing a plurality of clips lying one behind the other in the same plane, is mounted in the first handle. A feeder shoe is mounted in the clip tube and constantly urges the row of clips forwardly therein through the agency of a constant-force coil spring. Adjacent and along the clip tube, a pusher is mounted in the first handle in a pusher track which is continued to the forward ends of the jaws. The pusher is shiftable by the first and second handles between a retracted position when the handles are closed and an extended position to locate a clip in the pusher track between the forward ends of the jaws when the handles are open. The first handle provides a ramp structure leading to the pusher track at the forward end of the clip tube. The ramp structure is covered by the pusher when in its extended position. The ramp is exposed by the pusher when in its retracted position, enabling the forwardmost clip of the row to be transferred from the clip tube, via the ramp, to the pusher track in front of the pusher, due to the forward urging of the clips by the feeder shoe.
When the first and second handles are shifted from their closed to the open positions, the first and second jaws will also shift from their closed to the open positions and the pusher will locate a clip in the pusher track at a position between the forward ends of the jaws, ready for clamping. When the first and second handles are squeezed toward each other, the pusher will shift to its retracted position enabling the next forwardmost clip of the row to be ramped or transferred into the pusher track. Immediately thereafter, the first and second jaws will close, clamping the clip therebetween about the vessel to be occluded. This sequence of events is repeated with each opening and closing of the handles, the clip feeding system requiring no force on the part of the surgeon to accomplish its purpose.
In the use of a ligator of this general type, two problems are encountered. First of all, when the jaws, with a clip located therebetween, are caused to approach a vessel to be ligated, and when the vessel is located between the clip legs, any further advance of the jaws in the clip applying direction may cause the vessel to shift the clip rearwardly in the pusher track and out of its proper position for clamping between the jaws.
The above noted co-pending application teaches a solution of this problem comprising the provision of an integral pin mounted on the first jaw alongside the pusher track and extending toward the second jaw. The free end of the pin is receivable in a perforation in the second jaw when the jaws are closed to clamp a clip. The pin acts as a stop, limiting the depth to which the vessel to be ligated can enter between the jaws. Since the vessel abuts the pin, the vessel cannot shove the clip rearwardly beyond the pin.
U.S. Pat. No. 4,242,902 teaches a clip stop preventing rearward movement or displacement of the clip in the jaws of a ligating instrument. In the primary embodiment of this patent, a resilient arm-like member is provided having a free end which enters between the jaws and behind the clip. As the jaws are closed to clamp the clip, the free end of the stop is so configured as to be cammed out from between the jaws, by the jaws themselves.
The second problem frequently encountered in the use of the general type of ligator contemplated is the result of the accumulation of blood and/or other body fluids on the end of the pusher, rendering the pusher end tacky. Since, in the type of ligating instrument described above, the pusher retracts from between the jaws during the initial stages of the clip applying and clamping process, the clip sometimes tends to adhere to the pusher end and is retracted with the pusher end from between the jaws. The above noted U.S. Pat. No. 4,242,902 does not address this problem because the ligator taught therein does not have a pusher of the type contemplated. The stop pin described with respect to the above noted co-pending application does not solve this problem since it lies to the side of the pusher track and does not contact or engage the clip at any time.
The present invention contemplates a stop for a surgical ligating instrument wherein the stop prevents the clip from being shoved rearwardly in the pusher track during application and clamping thereof. Furthermore, the stop assures that the clip is separated from the pusher during the initial part of the clip-applying and clamping operation, when the pusher begins to retract from between the jaws. The stop itself is a simple structure made of resilient wire and remains between the jaws at all times.